Modeling and calculation of period for braced steel structures with semi-rigid joist-floor diaphragms

Authors

Abstract

In the Current seismic codes, the earthquake load on the buildings depends to period of structure. More of these codes use the empirical relations to estimate the period of structures. These relations are suggested for the rigid floor structures. Then use of these relations for semi-rigid and flexible diaphragms is not accurate and cause error in determination of seismic load of structures. This topic is more important for the stiffened structures such as: structures with shear wall or bracing together joist-floors with lower rigidity in one direction and semi-rigid behavior. In this paper, the period of the braced steel building with block-joist floors for two different cases of real modeling without rigid diaphragm assumption and ideal modeling with rigid diaphragm assumption are compared and effect of flexibility of diaphragms on the period of structure is investigated. Also, for fast estimation of period of structures with flexible diaphragms, the simple equations are proposed.

Keywords


[1]    صداقت، س، هادیانفرد، م، و لشکری، ع، مقایسه عملکرد سازه‌های فولادی با دیافراگم صلب و نیمه صلب در محدوده خطی و غیر‌خطی، ششمین کنفرانس بین‌المللی زلزله‌شناسی و مهندسی زلزله ، پژوهشگاه بین المللی زلزله شناسی و مهندسی زلزله، تهران، ایران، 1390.
[2]    صداقت، سعید، بررسی شرایط صلبیت و انعطاف پذیری سقف های تیرچه ای در سازه های فولادی مهاربندی شده و اثر آن بر طرح لرزه ای سازه در محدوده خطی و غیر خطی، پایان نامه کارشناسی ارشد، دانشکده مهندسی عمران، دانشگاه صنعتی شیراز،1390.
[3]    آیین‌نامه طرح ساختمان‌ها در برابر زلزله استاندارد 2800 ایران (ویرایش سوم)، کمیته تدوین آیین‌نامه طرح ساختمان‌ها در برابر زلزله،  انتشارات مرکز تحقیقات ساختمان و مسکن، تهران، 1384.
[4]                     Ju SH, Lin MC. Comparison of building analyses assuming rigid or flexible floors, Journal of Structural Engineering, 122, 439–445, 1996.
[5]                     Al Harash M, Panahshahi N, Truman K. Inelastic Seismic Response of Reinforced Concrete Buildings with Floor Diaphragm Openings, 14th World Conference on Earthquake Engineering, Structural and Environmental Engineering, Beijing, China, 2008.
[6]                     Sadashiva V.K., MacRae G.A., Deam B.L., Spooner M.S. Quantifying the seismic response of structures with flexible diaphragms, NZSEE Conference, 2009.
[7]                     Fleischman R. B, Sauser R, Pessiki S, Rhodes A. B. Seismic Behavior of Parking Structure Diaphragms, PCI Journal, 43,39–53, 1998.
[8]                     Barron J. M, Hueste M. B, Diaphragm Effects in Rectangular Reinforced Concrete, ACI Structural Journal, 101, 615-624, 2004.
[9]                     Hadianfard M. A, Sedaghat  S, Nonlinear Seismic Response of Braced Steel Structures With Flexible Block-Joist Floor,World Congress on Advances in Structural Engineering and Mechanics, Seoul, Korea, September, 2011.
[10]             Tremblay R, Stiemer S.F, Seismic behavior of single-storey steel structures with a flexible roof diaphragm. Canadian Journal of Civil Engineering, 23. 49-62,1996.
[11]             Sadashiva V.K., MacRae G. A., Deam B. L. and Spooner M. S, Quantifying the seismic response of structures with flexible diaphragms, Earthquake Engineering & Structural Dynamics, 41 (10), 1365–1389, 2012.
[12]             Humar J., Popovski M., Seismic response of single-storey buildings with flexible diaphragms, Canadian Journal of Civil Engineering, 40(9), 875-886, 2013.
[13]             Chopra A. K, Dynamics of structures: Theory and Applications to Earthquake Engineering. New Jersey, Prentice Hall.2000.